The present invention relates to a means for taking roller path inclination data as part of a weapons system alignment sequence. And more particularly to a servo-accelerometer sensor and signal conditioning circuitry capable of detecting very small angular displacements.
In order for a ship at sea to launch weaponry with the desied accuracy, part of the weapons system alignment sequence requires taking roller path inclination data so that all elements of the system will be referenced to the same reference plane. Ships at sea, however, are subject to pitch and roll; which motions affect the angular position of the ship with respect to the true vertical. Accordingly, as a ship rolls or pitches anything mounted on the ship, such as a weapons launching system would also become angularly offset from the true vertical.
Since the alignment of the weapon systems is done at night which is the time that ship and temperature conditions are the most stable, the human error factor is large. Eye fatigue from "marking a small bubble in a vial" is a great cause of error. Also, mental arithmetic suffers in the early morning hours, and many recording errors or calculations have caused reversed plots of data or wrong entries.
Bubble devices are an acceptable means of taking roller path inclination data if the allowable element tolerance is within the accuracy of the bubble device. It must be considered that use of a bubble device requires human judgment as to when the bubbles are matched during a data run, and therefore may affect the accuracy of the bubble device by as much as 20 arc seconds. Added to this are the ship flexure, ship load change, solar and thermal effects, and localized structural changes. It becomes obvious how difficult it is to attain a precise weapon element alignment. Also, in using the bubble devices, an operator is required at each element of the system when measurements are being made.